Vacuum-tube oscillator



- Jan. 25, 1927.

J. SLEPIAN vacuum TUBE OSCILLATOR Filed Feb. 26. 192i ATTORNEY Patented Jan. 25, 1927.

UNITED stares PATENTOF'FI-C-E.

JOSEPH SLEPIAN, OF SWISSVALE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

VACUUM-TUBE OSCILLATOR.

Application filed February 26, 1921. Serial No. 448,149.

My invention relates to oscillation-generator systems and more particularly to vacuum-tube systems that are employed in connection with wireless transmission systems.

The object of my invention is to provide a system of the above indicated character in which a two-electrode vacuum tube may be employed as a generator of high-frequency oscillations suitable for use in wire less transmission systems.

The use of the three-electrode vacuum tube as a generator of high-frequency oscillations is well known. In such systems, the vacuum tube may be brought to a condition of self oscillation by suitably coupling the plate-filament and grid-filament circuits through a so-call-ed feed-back or regenerative trans-former.

I have discovered that, with a suitabie arrangement of circuits, an efiiecient and reliable electron oscillation-generator system may be constructed which will utilize the effect of a transverse magnetic field upon the path of an electron.

In a vacuum tube, comprising a filament and an adjacently disposed anode, the electrons emitted from the heated filament travel in substantially straight lines to the anode. Upon the application of a transverse mag netic field, it is found that the path of the electrons become slightly curved and that the degree of curvature depends upon the intensity of the magnetic-field. Thus, with a magnetic field of sulficient intensity, the electrons may be caused to curve backwardly toward the cathode in cycloidal paths but never are permitted to reach it.

Briefly speaking, I cause the oscillations in the plate-filament circuit of a vacuumtube device to control the intensity of a mag netic field t'ansverse to the electron path whereby the vacuum-tube may function as an oscillation generator.

More specifically, my invention comprises a two-electrode vacuum-tube, a plate-filament circuit operatively connected thereto and including therein a source of energy and a, parallel-resonant circuit and a series-resonant circuit electrically connected to said parallel-resonant circuit. The inductance, which is included in the series-resonant circuit, is so disposed that the magnetic field therefrom is transverse to the electron path.

My invention may best be understood by reference to the accompanying drawing in which:

The single figure is a diagrammatic representation of circuits and apparatus embodying my invention, as applied to a wire less transmission system.

Referring to the single figure, an evacuated-electric device 1, which comprises a hot cathode 2 and an anode 3, is operatively connected to a radiating system through a plate-filament circuit and a coupling circuit 6. The hot cathode is energized from a source of energy 4 through the variable resister 5. The plate-filament circuit comprises a source of energy 7, a variable capacitance 8 for shunting the source of energy 7 and a parallel-resonant circuit 9 which comprises a variable capacitance 11 and an inductance 12. The period of the oscillations traversing the parallel-resonant circuit may be adjusted by varying either the capacitance 11 or the inductance 12.

A series-resonant circuit 13, which is operatively connected to the plate-filament circuit through the parallel-resonant circuit 9, comprises a variable capacitance 14:, an inductance 15 and a portion 16 of the inductance coil 12.

While I have shown an auto-transformer connection between the series-resonant and parallel-resonant circuits, it is obvious that my invention, in its broadest aspects, is not limited to such specific form of coupling between the pair of circuits.

A constant magnetic field is produced by means of the inductance 15 which is supplied from a source of energy 17 through a reactor 18. The inductance coil 15 is so disposed that its magnetic field is transverse to the electron path between the cathode 2 and the anode 3. The coupling circuit 6 comprises a coil 19 which is inductively related to the inductance coil 12 and a coil 20 which is inductively related to a coil 21 that is included in the antenna circuit. The antenna circuit comprises a radiating antenna 22, variable inductance 23, the coupling coil- 21, a variable capacitance 24: and a ground lead 25.

In operation, with the magnetic field adjusted to the critical point where the electrons are almost permitted to reach the anode and with the constants of the series and parallel-resonant circuits adjusted to such value that the flux produced by the coil 15 and the current in the plate-filament circuit are in phase, the tube is found to exhibit a negative-resistance characteristic. That is, upon an increase in the voltage in the plate-filament circuit and corresponding increase in the yalue of the flux produced by the coil 15, av corresponding decrease in the value of the current traversing the plate-filament circuit is eli'ected. Thus, my tube has a negative-resistance characteristic which, as is Well known, is a necessary condition for the generation of alternating currents from a direct-current source of energy.

The energy which has been transferred from the piate-iilament circuit to the antenna circuit through the coupling circuit 6 may be cont-rolled by any means Well known to the art, such, for example, as by means of a controlling key (not shown) for shunting a portion of the coil 21.

The particular advantage of: my invention is the provision of a simple, eiiicient and reliable 0scillation-generator system that is especially applicable to Wireless transmission systems.

Another advantage of my invention is the provision of an arrangement whereby the Well-known Fleming valve may be employed as a generator of alternating currents.

While I have shown only one embodiment of my invention, it is capable of various changes and modifications Without departing from the spirit of my invention. I desire, therefore, that only such limitations shall be imposed thereon as are indicated in the appended claim.

I claim as my invention:

In an oscillation-generator system, the combination with an evacuated-electric device including therein a space-current path, of a plate-filament circuit comprising a source of energy and a parallel-resoinint cir cuit and a series-resonant circuit operatively connected to said parallel-resonant circuit, Said circuitincluding therein a capacitance, an inductance and a circuit shunted around said inductance and including therein a source of energy and a reactor, the magnetic iield of said inductance being substantially transverse to the space-current path, and a radiating system operatively connected to said parallel-resonant circuit.

In testimony whereof, I have hereunto subscribed my name this 18th day of Feb ruary, 1921.

JOSEPH. SLEP] AN. 

